﻿Shader "ShaderBook/HalfLambert"
{
    Properties
    {
        _Diffuse("Diffuse", Color) = (1, 1, 1, 1)
    }
    SubShader
    {
        Pass
        {
            Tags{"LightMode" = "ForwardBase"}
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            
            #include "Lighting.cginc"
            fixed4 _Diffuse;

            struct a2v{
                float4 vertex : POSITION;
                float3 normal : NORMAL;
            };
            struct v2f{
                float4 pos : SV_POSITION;
                float3 worldNormal : TEXCOORD0;
            };

            v2f vert(a2v v){
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                o.worldNormal = mul(v.normal, (float3x3)unity_WorldToObject);
                return o;
            }
            
            fixed4 frag(v2f i) : SV_Target{
                fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz;
                fixed3 worldNormal = normalize(i.worldNormal);
                fixed3 worldLightDir = normalize(_WorldSpaceLightPos0.xyz);
                fixed3 halfLambert = dot(worldNormal, worldLightDir) * 0.5 + 0.5;
                fixed3 diffuse = _LightColor0.rgb * _Diffuse.rgb * halfLambert;
                fixed3 color = ambient + diffuse;
                return fixed4(color, 1.0);
            }

            ENDCG
        }
    }
    Fallback "Diffuse"
}
